Currently, a wireless terminal (for example, a cell phone, and a PDA) having a wireless fidelity (Wireless Fidelity, Wi-Fi) function has been widely applied. When a subscriber is in a large shopping mall or indoor, the subscriber can determine a location of the subscriber by using a wireless terminal that has a Wi-Fi function and is carried by the subscriber.
Referring to FIG. 1, FIG. 1 is a flow chart of a conventional wireless terminal (STA) positioning method. As shown in FIG. 1, the positioning method is introduced as follows: an STA first sends a positioning request message to an access point AP1, receives a measurement message returned by AP1, and possibly performs more message exchanges, aiming to obtain a transmission time T1 of a message between the STA and AP1; after completing message exchanges with AP1, the STA switches a channel and sends a positioning request message to AP2, and performs an exchange with AP2 to obtain a transmission time T2 of a message between the STA and AP2; after completing the message exchange with AP2, the STA switches a channel again and sends a positioning request message to AP3, and performs an exchange with AP3 to obtain a transmission time T3 of a message between the STA and AP3; . . . ; the rest may be deduced by analogy, and after the STA completes message exchanges with at least three APs, the STA may send T1, T2, T3 . . . to a location server, and the location server may be configured with a reference point database used to record a wireless transmission time between each sampled STA location and each AP, and therefore, the location server determines, according to T1, T2, T3 . . . sent by the STA, an STA location in the reference point database and notifies the STA, thereby realizing the positioning of the STA. The location server may also calculate the location of the STA through a triangulation positioning method after obtaining time information. The AP may also collect power information of the STA sending a location measurement message, and estimate the location of the STA by using signal intensity.
In the foregoing STA positioning method, the STA needs to perform a message exchange with each AP one by one, and sends a message in a contention-based manner. When the number of APs requiring exchanges is large and the number of subscribers is large, a long time is required for completing STA positioning once, and a large number of message exchanges consume more power of the STA.